1. Field of the Invention
The present invention relates to a method and apparatus for loading onto a printed wiring board solder balls which will become solder bumps.
2. Discussion of the Background
Solder bumps are used for electrical connection between a package substrate and an IC chip. Solder bumps are formed by the following steps:    (1) a step to print flux on electrodes formed in a package substrate;    (2) a step to load solder balls onto the electrodes on which the flux is printed; and    (3) a step to form solder bumps from the solder balls by a reflow.
In the above step to load solder balls onto electrodes, for example, as described in Japanese Patent No. 1975429, solder balls are suctioned by a suction head and then loaded onto electrodes. As described in Japanese Laid-Open Patent Application 2001-358450, using a ball array mask having multiple openings, solder balls are dropped onto electrodes. Japanese Laid-Open Patent Application 2001-267731 discloses another example method of loading solder balls. The entire contents of each of these publications are incorporated herein by reference.